For formation of elasticized waist bands and/or leg bands into disposable diapers, a method is known in the prior art, in which a laminate web used for production of a disposable diaper is stretched to impart elasticity to the web (PTL 1, for example). According to this method, in a step of incrementally stretching an unstretched laminate web, both the peripheral edge portions of a first elastomer layer and an extendable second layer are restrained so that the extendable second layer is permanently stretched by incremental stretching, in such a manner that the width of the laminate web in the stretching direction is the same as before application of stretching. Also, the pressure device used for stretching of the laminate web comprises a pair of corrugated rolls whose rotational axis lines are perpendicular to the movement direction of the web, the corrugated rolls having undulating three-dimensional surfaces, and the pair of corrugated rolls engaging each other when the unstretched laminated web passes between them. Also, by holding both the peripheral edge portions elastically, by holding both the peripheral edge portions with a pair of freely elastic deformable disks situated on the corrugated rolls, or by holding both the peripheral edge portions with a pair of continuous belts situated on the corrugated rolls, both the peripheral edge portions of the first elastomer layer and the extendable second layer are restrained.
According to the method for imparting elasticity to the web as described in PTL 1, when a portion of the web to be used for production of a disposable diaper passes between the pair of corrugated rolls, it is possible to prevent sliding and contraction of the web in the direction parallel to the direction of stretching of the web.